Tee-nut with globular shaped sleeve

ABSTRACT

A Tee-nut having a flange head, a plurality of prongs extending from the flange head, and a hollow sleeve extending from the flange head. The hollow sleeve has an internally threaded reduced diameter waist portion connecting to the flange head, and an enlarged globular bulbous portion extending from the internally threaded waist portion. The end of the enlarged bulbous portion is radiussed inwardly to facilitate insertion into a hole in a workpiece. Also disclosed is a workpiece fitted with such a Tee-nut.

FIELD OF THE INVENTION

The present invention relates to a Tee-nut and, in particular, to aTee-nut having a sleeve which shaped with a globular shape for ease ofinsertion and for enhanced retention.

BACKGROUND OF THE INVENTION

Fastener members, having a flange portion and a hollow sleeve portionwith a flarable end, are known and are commonly referred as Tee-nuts, orrivet type Tee-nuts. Other Tee nuts are available in which the Tee nutis simply inserted into a workpiece and is retained therein by spikesformed around the flange. In this specification, the term "Tee-nut" isused to describe such fastener members, whether of the flarable type orthe simple sleeve type.

Such Tee-nuts are usually formed of sheet metal, and provide a flangeportion with a plurality of fastening teeth or prongs, and a threadedsleeve, all formed out of a single piece of sheet metal.

Typically such Tee-nuts are used, for example, in furniture frames, forfastening the components of the furniture together. They also have avariety of other uses, both in furniture and in many other industries.

U.S. Pat. No. 5,348,432 granted to Nagayama on Sep. 20, 1994 discloses aTee-nut having a sleeve in the form of a hollow cylinder with arelatively thin-walled counterbored flarable end portion and arelatively thicker-walled threaded portion. The thin-walled flarablehollow sleeve end is formed by counter boring an internally threadedhollow sleeve. When flared outwardly, the thin-walled flarablecounter-bored end has a tendency to split, and the thin walled portionhas a tendency to collect wood chips internally in the threads, as theTee nut is driven in to the work piece.

U.S. Pat. No. 5,618,144, inventor Volkmar W. Leistner, title Tee-nutwith Enlarged Sleeve End, granted Apr. 8, 1997 and assigned to SigmaTool & Machine a Partnership of Sigma Tool & Machine Limited and SigmaFasteners Limited shows an improved form of Tee-nut with a flarable end.In this patent the Tee-nut sleeve is swaged out to enlarge its diameter,without intermediate reverse forming operations. However, these Tee-nutsrequire to be inserted into and through a bore in a wooden workpiece.The enlarged flarable leading end which was inserted first into the boretended in some cases, since the leading end of the open bore tended tocatch on the wood or tear particles of wood away. However these problemswere unusual since the holes in the workpiece were larger than thesleeve diameter, so as to admit the enlarged swaged out leading end.Enlarging the diameter of the hole meant that the Tee nut sleeve must besecurely flared so as to make a firm fit in the hole.

A further factor in the consideration of the manufacture of Tee nuts isthat where the Tee nuts are intended to be used without flaring, it hasbeen the practice to supply a simple Tee nut with a cylindrical sleeve,and where it was intended to flare the Tee nut then a special Tee nut offlarable design was provided instead. This may involve the user inbuying and storing two different types of Tee nuts, depending upon whichTee nut was to be used. Clearly it is desirable to provide a Tee nutwhich is adaptable to both types of installation, if it should becomenecessary to use a non-flaring Tee nut in place of a flaring Tee nut,and vice versa. It is further desirable to provide a flarable Tee nutwhich does not require the drilling of an oversize hole, so that agreater thickness of workpiece material is left around the hole forreception of the prongs.

Conversely it is desirable to provide a Tee nut which has a capacity forinsertion into a regular sized hole in a workpiece, and when inserted,producing a greater holding power than with conventional Tee nuts withregular cylindrical shaped sleeves.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a Tee-nut comprising a flange headmember, a plurality of prongs extending from said flange head member,and a sleeve member extending from said flange head member, said sleevemember being in the form of a hollow cylindrical sleeve comprising asleeve waist portion provided at the end of said sleeve memberconnecting to said flange head member, which is internally threaded anddefines a cylindrical portion, an enlarged generally globular bulbousportion extending from said internally threaded portion, wherein theouter globular surface of said bulbous portion has a larger diameterthan the outer diameter of said internally threaded cylindrical portion,and wherein the exterior surface of said globular bulbous portiondefines a smooth, curved shape in elevation, tapering outwardly fromsaid waist to a maximum diameter around said globular bulbous portion,and tapering inwardly once more to the free end of said sleeve.

The invention further provides a flarable Tee nut having these featuresand wherein the interior diameter of said enlarged globular bulbousportion is unthreaded and is flarable.

The invention further provides such a Tee nut wherein the open end ofthe globular bulbous portion is larger than the inner diameter of saidinternally threaded cylindrical waist portion such that a threading toolis adapted to pass through said globular flarable portion and operableto internally thread the interior of said waist portion of said sleevemember forming said internally threaded portion and wherein the end ofsaid globular bulbous flarable portion is radiussed inwardly.

The invention is used in workpieces having holes which are generallyminimally oversized relative to the waist diameter of the Tee-nut. Thisprovides added holding power in the workpiece due to the reduced radiusin the region of the waist which allows workpiece material to contractaround waist portion after the globular bulbous portion is inserted, tothus swell again around the waist portion, thereby gripping the globularbulbous portion and holding the Tee nut securely in place.

Because the flarable portion is globular in shape it slides more easilyinto the workpiece hole and does not pick up wood chips.

The various features of novelty which characterize the invention arepointed out with more particularity in the claims annexed to and forminga part of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated and described preferredembodiments of the invention.

IN THE DRAWINGS

FIG. 1 is a perspective view of a Tee-nut illustrating an embodiment ofthe present invention;

FIG. 2 is a top plan view of the Tee-nut of FIG. 1;

FIG. 3 is a sectional view taken along line 3--3 in FIG. 2; and

FIG. 4 is a section corresponding to FIG. 3 showing the Tee-nutcompletely inserted, and flared out.

DESCRIPTION OF A SPECIFIC EMBODIMENT

FIGS. 1 and 2 show a Tee-nut illustrating an embodiment of the presentinvention.

The Tee-nut, generally indicated by reference numeral 10, comprises anoctagon-shaped flange head 12, four integral prongs 14--14 extendingfrom the flange head 12, and an integral hollow sleeve 16 extendingperpendicular from the flange head 12.

The sleeve 16 comprises an internal threaded waist portion 18 and anenlarged globular bulbous portion 20.

The sleeve 16 from flange 12 to waist portion 18, defines a sleevejunction shaped as a progressively reducing radiussed portion, definingan arc.

The waist portion 18, has internal threads 22, in which a co-operatingthreaded screw member (not shown) is received. From portion 18 to theenlarged globular bulbous portion 20 is formed as a progressivelyexpanding radius defining an a smooth curve, in profile.

The outer shape of the enlarged globular bulbous portion 20 is of largerdiameter than the outer diameter of the internally threaded portion 18.The inner diameter of the enlarged globular bulbous portion 20 is largerthan the inner diameter of the internally threaded portion 18 such thata threading tool is enabled to pass through the enlarged globularbulbous portion 20, for internally threading waist 18 of the sleeve 16thus forming the internally threaded portion 18.

An inwardly radiussed leading end portion 24 is formed at the end of theenlarged globular bulbous portion 20. The radiussed leading end portion24 is formed by turning the outer end of globular bulbous portion 20inwardly by a suitable tool.

It will be seen that the exterior profile of the sleeve 16 is more orless that of a reduced diameter stem or waist with a globe-shaped end.The first portion of the sleeve 16 adjacent to the flange has a widerdiameter, which progressively reduces towards the waist portion 18. Thesleeve 16 is more or less cylindrical in the region of the interiorthreads at 18. The sleeve 16 then expands outwardly towards the maximumdiameter of the globular bulbous portion 24, after which it curvesprogressively inwardly at the leading end portion 20. Thus, the globularbulbous portion is somewhat in the form of a partial sphere or globe,with the sleeve 16, in the region of the waist portion 18 defining acontinuously convex arc in profile, so that the exterior shape of theTee-nut makes a smooth transition from concave to convex.

FIG. 3 shows a Tee-nut 10 after having been inserted into a pre-drilledhole 30 of a workpiece W, such as a piece of wood, or a panel ofchipboard, or other composite material. The diameter of the through hole30 is smaller than the outer diameter of the enlarged globular bulbousportion 20 of the Tee-nut 10. During the insertion process, the inwardlyraidussed leading end 24 has forced or wedged its way through the hole30, causing temporary displacement of part of the workpiece around thehole 30. As the waist portion 18 is finally seated in the hole 30, thesedisplaced portions of the workpiece will resume their normal shape, andwill snuggly engage the waist 18. In this way, the globular bulbousportion 20 is wedge fitted into the hole in the workpiece. At the sametime, the Tee-nut is more securely located and held in position.

The prongs 14--14 penetrate the workpiece W, around the hole 30. Sincethe hole 30 is of a smaller diameter to begin with, there will be agreater thickness of the workpiece around the hole 30 to receive theprongs 14. The prongs 14 thus prevent rotation of the Tee-nut 10 when athreaded screw member is being threadingly engaged to the internalthreaded portion 18.

The enlarged globular portion 20 is then flared out by means of aconventional flaring tool (not shown) in the hole 30, forming atrumpet-shaped flared end 26. The flared end 26 securely holds theTee-nut 10 within the pre-drilled through hole 30 of the workpiece 10and prevents the Tee-nut 10 from being withdrawn or pulled out from theworkpiece W.

It will of course be understood that while what is explained here is theuse of a rivet type Tee-nut, that the Tee-nut in accordance with thepresent invention may also be applicable to applications where it issimply inserted into a workpiece without any rivet or flaring action, ifit should be desired to use this type of Tee-nut in such an application.

The foregoing is a description of a preferred embodiment of theinvention which is given here by way of example only. The invention isnot to be taken as limited to any of the specific features as described,but comprehends all such variations thereof as come within the scope ofthe appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A Tee-nut for insertioninto a hole in a workpiece, the hole having a predetermined diameter,said Tee-nut having:a flange head member; a plurality of prongsextending from said flange head member; a hollow sleeve member extendingfrom said flange head member; said hollow sleeve member, comprising:ajunction portion adjacent said flange head member; an internallythreaded sleeve waist portion connecting to said junction portion; anenlarged globular bulbous semi-spherical sleeve portion extending fromsaid internally threaded waist portion, wherein the maximum outerdiameter of said enlarged flarable bulbous portion is larger than theouter diameter of said internally threaded waist portion, and whereinthe exterior profile of said enlarged globular bulbous portion defines acontinuous smoothly curved arc going from a minimum diameter at thewaist portion to a larger diameter at the largest region of saidglobular bulbous portion, and, an inwardly radiussed end on saidenlarged globular bulbous flarable portion.
 2. A Tee-nut as claimed inclaim 1 further comprising:wherein the said junction portion is formedin a progressively reducing radiussed fashion defining an arc.
 3. ATee-nut as claimed in claim 1 including:an opening defined in saidinwardly radiussed end, said opening defining a diameter larger than theinterior diameter of said internally threaded sleeve waist portion.
 4. Awooden workpiece having at least one Tee-nut embedded therein andcomprising;at least one hole extending through said workpiece said holehaving a predetermined diameter; a Tee-nut located in said hole andhaving a flange member; a plurality of prongs extending from said flangemember, and embedded into said workpiece; a hollow sleeve memberextending from said flange head member; said hollow sleeve member,comprising:a junction portion adjacent said flange head member; aninternally threaded sleeve waist portion connecting to said junctionportion; an enlarged globular bulbous semi-spherical sleeve portionextending from said internally threaded waist portion, wherein themaximum outer diameter of said enlarged flarable bulbous portion islarger than the outer diameter of said internally threaded waistportion, and wherein the exterior profile of said enlarged globularbulbous portion defines a continuous smoothly curved arc going from aminimum diameter at the waist portion to a larger diameter at thelargest region of said globular bulbous portion, and, an inwardlyradiussed end on said enlarged globular bulbous flarable portion.
 5. Awooden workpiece as claimed in claim 4 wherein said hole in saidworkpiece has a diameter less than that of said enlarged bulbous sleeveportion.
 6. A wooden workpiece as claimed in claim 5 wherein said freeend of said enlarged sleeve portion is swaged outwardly thereby securingsaid Tee-nut in said hole in said workpiece.
 7. A Tee-nut as claimed inclaim 4 further comprising:wherein the said junction portion is formedin a progressively reducing radiussed fashion defining an arc.
 8. ATee-nut as claimed in claim 4 including:an opening defined in saidinwardly radiussed end, said opening defining a diameter larger than theinterior diameter of said internally threaded sleeve waist portion.